Clutch and gear arrangement for a front wheel drive vehicle

ABSTRACT

A front wheel drive transmission is provided having an input member, an output member, four planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes a sun gear member, a planet carrier member, and a ring gear member. The torque transmitting devices include clutches and a brake arranged within a transmission housing. Each of the clutches and the brake are located within specific areas defined by the planetary gear sets and the housing walls.

FIELD

The invention relates generally to a multiple speed transmission having a plurality of planetary gear sets and a plurality of torque transmitting devices and more particularly to a transmission configured for a front wheel drive vehicle having eight or more speeds, five torque transmitting devices, and four planetary gear sets.

BACKGROUND

The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.

A typical multiple speed transmission uses a combination of a plurality of torque transmitting mechanisms, planetary gear arrangements and fixed interconnections to achieve a plurality of gear ratios. The number and physical arrangement of the planetary gear sets, generally, are dictated by packaging, cost and desired speed ratios.

While current transmissions achieve their intended purpose, the need for new and improved transmission configurations which exhibit improved performance, especially from the standpoints of efficiency, responsiveness and smoothness and improved packaging, primarily reduced size and weight, is essentially constant. Accordingly, there is a need for an improved, cost-effective, compact multiple speed transmission.

SUMMARY

In one aspect of the present invention, a transaxle is provided having a transmission input member, a transmission output member, a plurality of planetary gear sets, and a plurality of torque-transmitting mechanisms.

In another aspect of the present invention, the transmission includes a housing having a first wall, a second wall, and a third wall extending between the first and second walls. First, second, third and fourth planetary gear sets are disposed within the housing. Each planetary gear set includes a sun gear member, a ring gear member, and a planet carrier member supporting a plurality of planet gears each configured to intermesh with both the sun gear member and the ring gear member. The ring gear member of the first planetary gear set is permanently coupled to the sun gear member of the second planetary gear set, the ring gear member of the second planetary gear set is permanently coupled to the planet carrier member of the third planetary gear set, the ring gear member of the third planetary gear set is permanently coupled to the planet carrier member of the fourth planetary gear set, the sun gear member of the third planetary gear set is permanently coupled to the sun gear member of the fourth planetary gear set, the output member is permanently coupled with the carrier member of the fourth planetary gear set, the input member is permanently coupled with the carrier member of the first planetary gear set, and the sun gear member of the first planetary gear set is permanently coupled to the housing.

In another aspect of the present invention, the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the first planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and second planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the second and third planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall. A first clutch is disposed in at least one of the first, second, third, fourth, fifth, and sixth areas, a second clutch is disposed in at least one of the first, second, third, fourth, and sixth areas, a third clutch is disposed in at least one of the second, third, fourth, fifth and sixth areas, a fourth clutch is disposed in at least one of the second, third, fourth, and sixth areas, and a brake is disposed in at least one of the first, second, third, fourth, fifth, and sixth areas.

In yet another aspect of the present invention, a first clutch is disposed in at least one of the first, second, third, fourth, fifth, and sixth areas, a second clutch is disposed in at least one of the first, second, third, fourth, and sixth areas, a third clutch is disposed in at least one of the second, third, fourth, fifth and sixth areas, a fourth clutch is disposed in at least one of the second, third, fourth, and sixth areas, and a brake is disposed in at least one of the first, second, third, fourth, fifth, and sixth areas.

In yet another aspect of the present invention, the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the first planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and second planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the second and third planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall. A first clutch is disposed in at least one of the second, third, fourth, fifth, and sixth areas, a second clutch is disposed in at least one of the first, second, and sixth areas, a third clutch is disposed in at least one of the third, fourth, fifth and sixth areas, a fourth clutch is disposed in at least one of the second, third, and fifth areas, and a brake is disposed in at least one of the second, third, fourth, fifth, and sixth areas.

In yet another aspect of the present invention, the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the second planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and second planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and third planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall. A first clutch is disposed in at least one of the first, second, third, fourth, fifth, and sixth areas, a second clutch is disposed in at least one of the first, second, and sixth areas, a third clutch is disposed in at least one of the third, fourth, fifth and sixth areas, a fourth clutch is disposed in at least one of the second, third, and sixth areas, and a brake is disposed in at least one of the first, second, third, fourth, fifth, and sixth areas.

In yet another aspect of the present invention, the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the second planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and second planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and third planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall. A first clutch is disposed in at least one of the first, second, third, fourth, fifth, and sixth areas, a second clutch is disposed in at least one of the first, second, third, fourth, fifth, and sixth areas, a third clutch is disposed in at least one of the third, fourth, and sixth areas, a fourth clutch is disposed in at least one of the second, third, and sixth areas, and a brake is disposed in at least one of the first, second, third, fourth, fifth, and sixth areas.

In yet another aspect of the present invention, the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the third planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth and second planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the second and first planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall. A first clutch is disposed in at least one of the first, second, third, and sixth areas, a second clutch is disposed in at least one of the third, fourth, and fifth areas, a third clutch is disposed in at least one of the first, second, fifth, and sixth areas, a fourth clutch is disposed in at least one of the first, second, fifth, and sixth areas, and a brake is disposed in at least one of the first, second, third, and sixth areas.

In yet another aspect of the present invention, the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the second planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the second and third planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth and first planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall. A first clutch is disposed in at least one of the first, second, third, and sixth areas, a second clutch is disposed in at least one of the first, third, fourth, and sixth areas, a third clutch is disposed in at least one of the fourth, fifth, and sixth areas, a fourth clutch is disposed in at least one of the second, third, fourth, fifth, and sixth areas, and a brake is disposed in at least one of the first, second, third, fourth, and sixth areas.

In yet another aspect of the present invention, the clutches and the brake are selectively engageable to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member.

In yet another aspect of the present invention, the first clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the ring gear member of the fourth planetary gear set, the second clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the planet carrier member of the first planetary gear set and the input member, the third clutch is selectively engageable to interconnect the planet carrier member of the first planetary gear set and the input member with the sun gear members of the third and fourth planetary gear sets, the fourth clutch is selectively engageable to interconnect the ring gear member of the first planetary gear set and the sun gear member of the second planetary gear set with the sun gear members of the third and fourth planetary gear sets, and the brake is selectively engageable to interconnect the ring gear member of the fourth planetary gear set to the housing.

In yet another aspect of the present invention, the transaxle includes a transfer gear train having a first transfer gear intermeshed with a second transfer gear, wherein the first transfer gear is rotatably fixed to the output member and the second transfer gear is rotatably fixed to an intermediate shaft, a differential gear set for driving a pair of road wheels, a pinion gear rotatably fixed to the intermediate shaft, and an input differential gear in mesh with the pinion gear and configured to rotatably drive the differential gear set.

In yet another aspect of the present invention, the transaxle includes a power transfer assembly having a first transfer gear and a second transfer gear, wherein the first transfer gear is rotatably fixed to the output member and the second transfer gear is rotatably fixed to a drive shaft, a power transfer member rotatably coupling the first and second transfer gears for transferring rotational energy from the first transfer gear to the second transfer gear, a final drive planetary gear set coupled to the drive shaft for receiving a driving torque from the second transfer gear, and a differential gear set coupled to the final drive planetary gear set and to a pair of road wheels for receiving a final drive rotational torque and transferring the final drive torque to the pair of road wheels.

Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

FIG. 1A is a schematic diagram of a gear arrangement for a front wheel drive transmission according to the principles of the present invention;

FIG. 1B is a chart showing the locations of the torque transmitting devices for the arrangement of planetary gear sets of the transmission shown in FIG. 1A, in accordance with the embodiments of the present invention;

FIG. 2A is another schematic diagram of a gear arrangement for a front wheel drive transmission according to the principles of the present invention;

FIG. 2B is a chart showing the locations of the torque transmitting devices for the arrangement of planetary gear sets of the transmission shown in FIG. 2A, in accordance with the embodiments of the present invention;

FIG. 3A is another schematic diagram of a gear arrangement for a front wheel drive transmission according to the principles of the present invention;

FIG. 3B is a chart showing the locations of the torque transmitting devices for the arrangement of planetary gear sets of the transmission shown in FIG. 3A, in accordance with the embodiments of the present invention;

FIG. 4A is another schematic diagram of a gear arrangement for a front wheel drive transmission according to the principles of the present invention;

FIG. 4B is a chart showing the locations of the torque transmitting devices for the arrangement of planetary gear sets of the transmission shown in FIG. 4A, in accordance with the embodiments of the present invention;

FIG. 5A is another schematic diagram of a gear arrangement for a front wheel drive transmission according to the principles of the present invention;

FIG. 5B is a chart showing the locations of the torque transmitting devices for the arrangement of planetary gear sets of the transmission shown in FIG. 5A, in accordance with the embodiments of the present invention;

FIG. 6A is another schematic diagram of a gear arrangement for a front wheel drive transmission according to the principles of the present invention;

FIG. 6B is a chart showing the locations of the torque transmitting devices for the arrangement of planetary gear sets of the transmission shown in FIG. 6A, in accordance with the embodiments of the present invention;

FIG. 7 is a schematic diagram of a front wheel drive transaxle arrangement incorporating the gear arrangement of the transmission of FIGS. 1A-6A, according to the principles of the present invention; and

FIG. 8 is another schematic diagram of a front wheel drive transaxle arrangement incorporating the gear arrangement of the transmission of FIGS. 1A-6A, according to the principles of the present invention.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

Referring now to FIG. 1A, an embodiment of a front wheel drive multi-speed or eight speed transmission is generally indicated by reference number 10. The transmission 10 is illustrated as a front wheel drive or transverse transmission, though various other types of transmission configurations may be employed. The transmission 10 includes a transmission housing 12, an input shaft or member 14, an output shaft or member 16 and a gear arrangement 18. The input member 14 is continuously connected to an engine (shown in FIGS. 7 and 8) or to a turbine of a torque converter (not shown). The output member 16 is continuously connected with a final drive unit (not shown) or transfer case (shown in FIGS. 7 and 8).

The gear arrangement 18 of transmission 10 includes a first planetary gear set 20, a second planetary gear set 22, a third planetary gear set 24, and a fourth planetary gear set 26. The planetary gear sets 20, 22, 24 and 26 are connected between the input member 14 and the output member 16.

In a preferred embodiment of the present invention, the planetary gear set 20 includes a sun gear member 20C, a ring gear member 20A, and a planet carrier member 20B that rotatably supports a set of planet or pinion gears 20D (only one of which is shown). The sun gear member 20C is connected to transmission housing 12 with a first shaft or intermediate member 42. The ring gear member 20A is connected for common rotation with a second shaft or intermediate member 44. The planet carrier member 20B is connected for common rotation with input shaft or member 14 and a third shaft or intermediate member 46. The pinion gears 20D are configured to intermesh with the sun gear member 20C and the ring gear member 20A.

The planetary gear set 22 includes a ring gear member 22A, a planet carrier member 22B that rotatably supports a set of planet or pinion gears 22D and a sun gear member 22C. The ring gear member 22A is connected for common rotation with a fourth shaft or intermediate member 48. The sun gear member 22C is connected for common rotation with the second shaft or intermediate member 44. The planet carrier member 22B is connected for common rotation with a fifth shaft or intermediate member 50. The pinion gears 22D are configured to intermesh with the sun gear member 22C and the ring gear member 22A.

The planetary gear set 24 includes a ring gear member 24A, a planet carrier member 24B that rotatably supports a set of planet or pinion gears 24D and a sun gear member 24C. The ring gear member 24A is connected for common rotation with a sixth shaft or intermediate member 52. The sun gear member 24C is connected for common rotation with a seventh shaft or intermediate member 54. The planet carrier member 24B is connected for common rotation with the fourth shaft or intermediate member 48. The pinion gears 24D are configured to intermesh with the sun gear member 24C and the ring gear member 24A.

The planetary gear set 26 includes a sun gear member 26C, a ring gear member 26A, and a carrier member 26B that rotatably supports a set of planet or pinion gears 26D. The sun gear member 26C is connected for common rotation with the seventh shaft or intermediate member 54. The ring gear member 26A is connected for common rotation with an eighth shaft or intermediate member 56. The planet carrier member 26B is connected for common rotation with the output shaft or member 16 and the sixth shaft or intermediate member 52. The pinion gears 26D are configured to intermesh with the sun gear member 26C and the ring gear member 26A.

The transmission 10 also includes a plurality of torque-transmitting mechanisms or devices including a first clutch 28, a second clutch 30, a third clutch 32, a fourth clutch 34 and a brake 36. The first clutch 28 is selectively engagable to connect the fifth shaft or intermediate member 50 to the eighth shaft or intermediate member 56. The second clutch 30 is selectively engagable to connect the input shaft or member 14 and the third shaft or interconnecting member 46 to the fifth intermediate member 50. The third clutch 32 is selectively engagable to connect the third intermediate member 46 and the input member 14 to the seventh intermediate shaft or member 54. The fourth clutch 34 is selectively engagable to connect the second shaft or intermediate member 44 to the seventh shaft or intermediate member 54. Finally, the brake 36 is selectively engagable to connect the eighth intermediate member 56 to the transmission housing 12 to restrict rotation of the member 56 relative to the transmission housing 12.

The transmission 10 is capable of transmitting torque from the input shaft or member 14 to the output shaft or member 16 in at least eight forward torque ratios and one reverse torque ratio. Each of the forward torque ratios and the reverse torque ratio are attained by engagement of one or more of the torque-transmitting mechanisms (i.e. first clutch 28, second clutch 30, third clutch 32, fourth clutch 34 and brake 36). Those skilled in the art will readily understand that a different speed ratio is associated with each torque ratio. Thus, eight forward speed ratios may be attained by the transmission 10.

The transmission housing 12 includes a first wall or structural member 102, a second wall or structural member 104 and a third wall or structural member 106. The third wall 106 interconnects the first and second walls 102 and 104 to define a space or cavity 110. The input shaft or member 14 and output shaft or member 16 are supported by the second wall 104 by bearings 112. The planetary gear sets 20, 22, 24 and 26 and the torque-transmitting mechanisms 28, 30, 32, 34 and 36 are disposed within cavity 110. Further, the cavity 110 has a plurality of areas or zones A, B, C, D, E, and F in which the plurality of torque transmitting mechanisms 28, 30, 32, 34 and 36 will be specifically positioned or mounted, in accordance with the preferred embodiments of the present invention.

As shown in FIG. 1A, zone A is defined by the area or space bounded by: the first wall 102, planetary gear set 20, radially inward by a reference line “L” which is a longitudinal line that is axially aligned with the input shaft 14, and radially outward by a reference line “M” which is a longitudinal line that extends adjacent an outer diameter or outer periphery of the planetary gear sets 20, 22, 24 and 26. While reference line “M” is illustrated as a straight line throughout the several views, it should be appreciated that reference line “M” follows the outer periphery of the planetary gear sets 20, 22, 24 and 26, and accordingly may be stepped or non-linear depending on the location of the outer periphery of each of the planetary gear sets 20, 22, 24 and 26. Zone B is defined by the area bounded by: planetary gear set 20, the planetary gear set 22, radially outward by reference line “M”, and radially inward by reference line “L”. Zone C is defined by the area bounded by: the planetary gear set 22, the planetary gear set 24, radially outward by reference line “M”, and radially inward by reference line “L”. Zone D is defined by the area bounded by: the planetary gear set 24, the planetary gear set 26, radially outward by reference line “M”, and radially inward by reference line “L”. Zone E is defined by the area bounded by: the planetary gear set 26, the second end wall 104, radially outward by reference line “M”, and radially inward by reference line “L”. Zone F is defined by the area bounded by: the first wall 102, the second wall 104, radially inward by reference line “M” and radially outward by the third wall 106.

In the gear arrangement 18 of transmission 10 shown in FIG. 1A, the planetary gear set 20 is disposed closest to the first wall 102, the planetary gear set 26 is disposed closest to the second wall 104, the planetary gear set 22 is adjacent the planetary gear set 20, and the planetary gear set 24 is disposed between the planetary gear sets 22 and 26. The torque-transmitting mechanisms are intentionally located within specific Zones in order to provide advantages in overall transmission size, packaging efficiency, and reduced manufacturing complexity. In the particular example shown in FIG. 1A, the first clutch 28 is disposed in Zone F, the second clutch 30 is disposed in Zone A, the third clutch 32 and the brake 36 are disposed in Zone E, and the fourth clutch 34 is disposed in Zone C.

However, the present invention contemplates other embodiments where the torque-transmitting mechanisms 28, 30, 32, 34 and 36 are disposed in the other Zones. The feasible locations of the torque-transmitting mechanisms 28, 30, 32, 34 and 36 within the Zones are illustrated in the chart shown in FIG. 1B. The chart of FIG. 1B lists clutches and the brake in the left most column and the available zones to locate the clutch/brake in the top row. An “X” in the chart indicates that the present invention contemplates locating the clutch or brake in the zone listed in the top row. For example, brake 36 may be located in Zones A, B, C, D, E, or F and fourth clutch 34 may be located in zones B, C, D, or F.

Referring now to FIG. 2A, another embodiment of a transmission is generally indicated by reference number 100. The transmission 100 is similar to transmission 10 and like components are indicated by like reference numbers. However, the transmission 100 includes an alternate gear arrangement 118 where the first interconnecting member 42 is fixed to the top wall 106 and the second and third interconnecting members 44 and 46 are nested (i.e. are sleeve shafts) with the input member 14.

The torque-transmitting mechanisms are intentionally located within specific Zones in order to provide advantages in overall transmission size, packaging efficiency, and reduced manufacturing complexity. In the particular example shown in FIG. 2A, the first clutch 28 and the second clutch 30 are disposed in Zone B, the third clutch 32 and the brake 36 are disposed in Zone E, and the fourth clutch 34 is disposed in Zone C.

However, the present invention contemplates other embodiments where the torque-transmitting mechanisms 28, 30, 32, 34 and 36 are disposed in the other Zones. The feasible locations of the torque-transmitting mechanisms 28, 30, 32, 34 and 36 within the Zones are illustrated in the chart shown in FIG. 2B. The chart of FIG. 2B lists clutches and the brake in the left most column and the available zones to locate the clutch/brake in the top row. An “X” in the chart indicates that the present invention contemplates locating the clutch or brake in the zone listed in the top row. For example, brake 36 may be located in Zones B, C, D, E, or F and fourth clutch 34 may be located in zones B, C, or E.

Referring now to FIG. 3A, another embodiment of a transmission is generally indicated by reference number 200. The transmission 200 is similar to transmission 10 and like components are indicated by like reference numbers. However, as shown in FIG. 3A, zone A is defined by the area or space bounded by: the first wall 102, planetary gear set 22, radially inward by a reference line “L” which is a longitudinal line that is axially aligned with the input shaft 14, and radially outward by a reference line “M” which is a longitudinal line that extends adjacent an outer diameter or outer periphery of the planetary gear sets 20, 22, 24 and 26. While reference line “M” is illustrated as a straight line throughout the several views, it should be appreciated that reference line “M” follows the outer periphery of the planetary gear sets 20, 22, 24 and 26, and accordingly may be stepped or non-linear depending on the location of the outer periphery of each of the planetary gear sets 20, 22, 24 and 26. Zone B is defined by the area bounded by: planetary gear set 22, the planetary gear set 20, radially outward by reference line “M”, and radially inward by reference line “L”. Zone C is defined by the area bounded by: the planetary gear set 20, the planetary gear set 24, radially outward by reference line “M”, and radially inward by reference line “L”. Zone D is defined by the area bounded by: the planetary gear set 24, the planetary gear set 26, radially outward by reference line “M”, and radially inward by reference line “L”. Zone E is defined by the area bounded by: the planetary gear set 26, the second end wall 104, radially outward by reference line “M”, and radially inward by reference line “L”. Zone F is defined by the area bounded by: the first wall 102, the second wall 104, radially inward by reference line “M” and radially outward by the third wall 106.

In the gear arrangement 218 of transmission 200 shown in FIG. 3A, the planetary gear set 22 is disposed closest to the first wall 102, the planetary gear set 26 is disposed closest to the second wall 104, the planetary gear set 20 is adjacent the planetary gear set 22, and the planetary gear set 24 is disposed between the planetary gear sets 20 and 26. The torque-transmitting mechanisms are intentionally located within specific Zones in order to provide advantages in overall transmission size, packaging efficiency, and reduced manufacturing complexity. In the particular example shown in FIG. 3A, the first clutch 28 and the brake 36 are disposed in Zone F, the second clutch 30 is disposed in Zone A, the third clutch 32 and the fourth clutch 34 are disposed in Zone C.

However, the present invention contemplates other embodiments where the torque-transmitting mechanisms 28, 30, 32, 34 and 36 are disposed in the other Zones. The feasible locations of the torque-transmitting mechanisms 28, 30, 32, 34 and 36 within the Zones are illustrated in the chart shown in FIG. 3B. The chart of FIG. 3B lists clutches and the brake in the left most column and the available zones to locate the clutch/brake in the top row. An “X” in the chart indicates that the present invention contemplates locating the clutch or brake in the zone listed in the top row. For example, brake 36 may be located in Zones A, B, C, D, E, or F and fourth clutch 34 may be located in zones B, C, or F.

Referring now to FIG. 4A, another embodiment of a transmission is generally indicated by reference number 300. The transmission 300 is similar to transmission 200 and like components are indicated by like reference numbers. However, the transmission 300 includes an alternate gear arrangement 318 where the first interconnecting member 42 is fixed to the wall 104 and the location of the third interconnecting member 46 and the input member 14 are switched relative to planetary gear set 20.

The torque-transmitting mechanisms are intentionally located within specific Zones in order to provide advantages in overall transmission size, packaging efficiency, and reduced manufacturing complexity. In the particular example shown in FIG. 4A, the first clutch 28 is disposed in Zone F, the second clutch 30 is disposed in Zone A, the third clutch 32 and the fourth clutch 34 are disposed in Zone C, and the brake 36 is disposed in Zone E.

However, the present invention contemplates other embodiments where the torque-transmitting mechanisms 28, 30, 32, 34 and 36 are disposed in the other Zones. The feasible locations of the torque-transmitting mechanisms 28, 30, 32, 34 and 36 within the Zones are illustrated in the chart shown in FIG. 4B. The chart of FIG. 4B lists clutches and the brake in the left most column and the available zones to locate the clutch/brake in the top row. An “X” in the chart indicates that the present invention contemplates locating the clutch or brake in the zone listed in the top row. For example, brake 36 may be located in Zones A, B, C, D, E, or F and fourth clutch 34 may be located in zones B, C, or F.

Referring now to FIG. 5A, another embodiment of a transmission is generally indicated by reference number 400. The transmission 400 is similar to transmission 10 and like components are indicated by like reference numbers. However, as shown in FIG. 5A, Zone A is defined by the area or space bounded by: the first wall 102, planetary gear set 24, radially inward by a reference line “L” which is a longitudinal line that is axially aligned with the input shaft 14, and radially outward by a reference line “M” which is a longitudinal line that extends adjacent an outer diameter or outer periphery of the planetary gear sets 20, 22, 24 and 26. While reference line “M” is illustrated as a straight line throughout the several views, it should be appreciated that reference line “M” follows the outer periphery of the planetary gear sets 20, 22, 24 and 26, and accordingly may be stepped or non-linear depending on the location of the outer periphery of each of the planetary gear sets 20, 22, 24 and 26. Zone B is defined by the area bounded by: planetary gear set 24, the planetary gear set 26, radially outward by reference line “M”, and radially inward by reference line “L”. Zone C is defined by the area bounded by: the planetary gear set 26, the planetary gear set 22, radially outward by reference line “M”, and radially inward by reference line “L”. Zone D is defined by the area bounded by: the planetary gear set 22, the planetary gear set 20, radially outward by reference line “M”, and radially inward by reference line “L”. Zone E is defined by the area bounded by: the planetary gear set 20, the second end wall 104, radially outward by reference line “M”, and radially inward by reference line “L”. Zone F is defined by the area bounded by: the first wall 102, the second wall 104, radially inward by reference line “M” and radially outward by the third wall 106.

In the gear arrangement 418 of transmission 400 shown in FIG. 5A, the planetary gear set 24 is disposed closest to the first wall 102, the planetary gear set 20 is disposed closest to the second wall 104, the planetary gear set 26 is adjacent the planetary gear set 24, and the planetary gear set 22 is disposed between the planetary gear sets 26 and 20. The torque-transmitting mechanisms are intentionally located within specific Zones in order to provide advantages in overall transmission size, packaging efficiency, and reduced manufacturing complexity. In the particular example shown in FIG. 5A, the first clutch 28 and the brake 36 are disposed in Zone F, the second clutch 30 is disposed in Zone D, and the third clutch 32 and the fourth clutch 34 are disposed in Zone E.

However, the present invention contemplates other embodiments where the torque-transmitting mechanisms 28, 30, 32, 34 and 36 are disposed in the other Zones. The feasible locations of the torque-transmitting mechanisms 28, 30, 32, 34 and 36 within the Zones are illustrated in the chart shown in FIG. 5B. The chart of FIG. 5B lists clutches and the brake in the left most column and the available zones to locate the clutch/brake in the top row. An “X” in the chart indicates that the present invention contemplates locating the clutch or brake in the zone listed in the top row. For example, brake 36 may be located in Zones A, B, C, or F and fourth clutch 34 may be located in zones A, B, E, or F.

Referring now to FIG. 6A, another embodiment of a transmission is generally indicated by reference number 500. The transmission 500 is similar to transmission 10 and like components are indicated by like reference numbers. However, as shown in FIG. 6A, Zone A is defined by the area or space bounded by: the first wall 102, planetary gear set 22, radially inward by a reference line “L” which is a longitudinal line that is axially aligned with the input shaft 14, and radially outward by a reference line “M” which is a longitudinal line that extends adjacent an outer diameter or outer periphery of the planetary gear sets 20, 22, 24 and 26. While reference line “M” is illustrated as a straight line throughout the several views, it should be appreciated that reference line “M” follows the outer periphery of the planetary gear sets 20, 22, 24 and 26, and accordingly may be stepped or non-linear depending on the location of the outer periphery of each of the planetary gear sets 20, 22, 24 and 26. Zone B is defined by the area bounded by: planetary gear set 22, the planetary gear set 24, radially outward by reference line “M”, and radially inward by reference line “L”. Zone C is defined by the area bounded by: the planetary gear set 24, the planetary gear set 26, radially outward by reference line “M”, and radially inward by reference line “L”. Zone D is defined by the area bounded by: the planetary gear set 26, the planetary gear set 20, radially outward by reference line “M”, and radially inward by reference line “L”. Zone E is defined by the area bounded by: the planetary gear set 20, the second end wall 104, radially outward by reference line “M”, and radially inward by reference line “L”. Zone F is defined by the area bounded by: the first wall 102, the second wall 104, radially inward by reference line “M” and radially outward by the third wall 106.

In the gear arrangement 518 of transmission 500 shown in FIG. 6A, the planetary gear set 22 is disposed closest to the first wall 102, the planetary gear set 20 is disposed closest to the second wall 104, the planetary gear set 24 is adjacent the planetary gear set 22, and the planetary gear set 26 is disposed between the planetary gear sets 24 and 20. The torque-transmitting mechanisms are intentionally located within specific Zones in order to provide advantages in overall transmission size, packaging efficiency, and reduced manufacturing complexity. In the particular example shown in FIG. 6A, the first clutch 28 and the second clutch 30 are disposed in Zone A, the third clutch 32 and the fourth clutch 34 are disposed in Zone E, and the brake is disposed in Zone F.

However, the present invention contemplates other embodiments where the torque-transmitting mechanisms 28, 30, 32, 34 and 36 are disposed in the other Zones. The feasible locations of the torque-transmitting mechanisms 28, 30, 32, 34 and 36 within the Zones are illustrated in the chart shown in FIG. 6B. The chart of FIG. 6B lists clutches and the brake in the left most column and the available zones to locate the clutch/brake in the top row. An “X” in the chart indicates that the present invention contemplates locating the clutch or brake in the zone listed in the top row. For example, brake 36 may be located in Zones A, B, C, D, or F and fourth clutch 34 may be located in zones B, C, D, E, or F.

Referring now to FIG. 7, a front wheel drive powertrain 600 incorporating a transaxle 602 is illustrated, in accordance with the embodiments of the present invention. Transaxle 602 includes the transmission 10 having the gear arrangement 18 shown in FIGS. 1A and 1B. However, it should be appreciated that the transaxle 602 may incorporate any of the transmissions 10, 100, 200, 300, 400, and 500 having any of the gear arrangements 18, 118, 218, 318, 418, and 518 shown in FIGS. 1A through 6B without departing from the scope of the present invention. Transmission 10 is mounted to an engine 604. Engine 604 provides a driving torque through input shaft 14 to transmission 10. Engine 604 is generally an internal combustion engine, however, the present invention contemplates other types of engines such as electric and hybrid engines. Further, transaxle 602 includes a transfer gear train 606, a differential 608, and a pair of drive axles 610 and 612 that drive a pair of road wheels 614 and 616, respectively.

Transfer gear train 606 includes a first transfer gear 618 and a second transfer gear 620. Output shaft or member 16 is coupled to the first transfer or spur gear 618. First transfer gear 618 may be a straight spur gear having straight gear teeth or a helical gear having helical gear teeth. First transfer gear 618 meshes with the second transfer gear 620. Second transfer gear 620 is rotatably fixed to an intermediate shaft or rotatable member 622. Further, a pinion 624 is mounted to shaft 622 and intermeshes with an input differential gear 626. Input differential gear 626 transfers driving torque to the differential 608. Differential 608, as conventionally known, transfers the driving torque generated by engine 604 to the two drive axles 610 and 612. Drive axles 610 and 612 are independently driven by differential 608 to supply the driving torque to the vehicle road wheels 614 and 616.

Referring now to FIG. 8, another embodiment of a front wheel drive powertrain 700 incorporating a transaxle 702 is illustrated, in accordance with the embodiments of the present invention. Transaxle 702 includes the transmission 10 having the gear arrangement 18 shown in FIGS. 1A and 1B. However, it should be appreciated that the transaxle 702 may incorporate any of the transmissions 10, 100, 200, 300, 400, and 500 having any of the gear arrangements 18, 118, 218, 318, 418, and 518 shown in FIGS. 1A through 6B without departing from the scope of the present invention. Transmission 10 is mounted to an engine 704. Engine 704 provides a driving torque through input shaft 14 to transmission 10. Further, transaxle 702 includes a transfer chain 706, a driven sprocket or gear 708, a differential 710, a final drive planetary gear set 712 and a pair of drive axles 714 and 716 that drive a pair of road wheels 718 and 720, respectively.

Transfer chain 706 engages at a first end 722 a drive sprocket or gear 724 and at a second end 726 the driven sprocket or gear 708. The drive sprocket 724 is coupled to output shaft or member 16. Driven sprocket 708 is rotatably fixed to a drive shaft or rotatable member 728. Further, drive shaft 728 is coupled to the sun gear of the final drive planetary gear set 712 to achieve the desired gear ratio. The final drive planetary gear set 712 transfers driving torque to the differential 710 though the carrier member of the final drive planetary gear set 712 to the housing of the differential 710. Differential 710, as conventionally known, transfers the driving torque generated by engine 704 to the two drive axles 714 and 716 through bevel gears of differential 710. Drive axles 714 and are independently driven by differential 710 to supply the driving torque to the vehicle road wheels 718 and 720.

The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention. 

1. A transaxle comprising: an input member; an output member; a housing having a first wall, a second wall, and a third wall extending between the first and second walls; first, second, third and fourth planetary gear sets disposed within the housing, wherein the first planetary gear set is adjacent the first wall, the fourth planetary gear set is adjacent second wall, the second planetary gear set is adjacent the first planetary gear set and the third planetary gear set is between the second and fourth planetary gear sets, each planetary gear set having a sun gear member, a ring gear member, and a planet carrier member supporting a plurality of planet gears each configured to intermesh with both the sun gear member and the ring gear member, and wherein the ring gear member of the first planetary gear set is permanently coupled to the sun gear member of the second planetary gear set, the ring gear member of the second planetary gear set is permanently coupled to the planet carrier member of the third planetary gear set, the ring gear member of the third planetary gear set is permanently coupled to the planet carrier member of the fourth planetary gear set, the sun gear member of the third planetary gear set is permanently coupled to the sun gear member of the fourth planetary gear set, the output member is permanently coupled with the carrier member of the fourth planetary gear set, the input member is permanently coupled with the carrier member of the first planetary gear set, and the sun gear member of the first planetary gear set is permanently coupled to the first wall of the housing, and wherein the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the first planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and second planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the second and third planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall; a first clutch disposed in at least one of the first, second, third, fourth, fifth, and sixth areas; a second clutch disposed in at least one of the first, second, third, fourth, and sixth areas; a third clutch disposed in at least one of the second, third, fourth, fifth and sixth areas; a fourth clutch disposed in at least one of the second, third, fourth, and sixth areas; a brake disposed in at least one of the first, second, third, fourth, fifth, and sixth areas, and wherein the clutches and the brake are selectively engageable to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member; a transfer gear train having a first transfer gear intermeshed with a second transfer gear, wherein the first transfer gear is rotatably fixed to the output member and the second transfer gear is rotatably fixed to an intermediate shaft; a differential gear set for driving a pair of road wheels; a pinion gear rotatably fixed to the intermediate shaft; and an input differential gear in mesh with the pinion gear and configured to rotatably drive the differential gear set.
 2. The transaxle of claim 1 wherein the first clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the ring gear member of the fourth planetary gear set, the second clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the planet carrier member of the first planetary gear set and the input member, the third clutch is selectively engageable to interconnect the planet carrier member of the first planetary gear set and the input member with the sun gear members of the third and fourth planetary gear sets, the fourth clutch is selectively engageable to interconnect the ring gear member of the first planetary gear set and the sun gear member of the second planetary gear set with the sun gear members of the third and fourth planetary gear sets, and the brake is selectively engageable to interconnect the ring gear member of the fourth planetary gear set to the housing.
 3. The transaxle of claim 2 wherein the first clutch is disposed in the sixth area, the second clutch is disposed in the first area, the third clutch is disposed in the fifth area, the fourth clutch is disposed in the third area, and the brake is disposed in the fifth area.
 4. A transaxle comprising: an input member; an output member; a housing having a first wall, a second wall, and a third wall extending between the first and second walls; first, second, third and fourth planetary gear sets disposed within the housing, wherein the first planetary gear set is adjacent the first wall, the fourth planetary gear set is adjacent second wall, the second planetary gear set is adjacent the first planetary gear set and the third planetary gear set is between the second and fourth planetary gear sets, each planetary gear set having a sun gear member, a ring gear member, and a planet carrier member supporting a plurality of planet gears each configured to intermesh with both the sun gear member and the ring gear member, and wherein the ring gear member of the first planetary gear set is permanently coupled to the sun gear member of the second planetary gear set, the ring gear member of the second planetary gear set is permanently coupled to the planet carrier member of the third planetary gear set, the ring gear member of the third planetary gear set is permanently coupled to the planet carrier member of the fourth planetary gear set, the sun gear member of the third planetary gear set is permanently coupled to the sun gear member of the fourth planetary gear set, the output member is permanently coupled with the carrier member of the fourth planetary gear set, the input member is permanently coupled with the carrier member of the first planetary gear set, and the sun gear member of the first planetary gear set is permanently coupled to the first wall of the housing, and wherein the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the first planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and second planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the second and third planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall; a first clutch disposed in at least one of the first, second, third, fourth, fifth, and sixth areas; a second clutch disposed in at least one of the first, second, third, fourth, and sixth areas; a third clutch disposed in at least one of the second, third, fourth, fifth and sixth areas; a fourth clutch disposed in at least one of the second, third, fourth, and sixth areas; a brake disposed in at least one of the first, second, third, fourth, fifth, and sixth areas, and wherein the clutches and the brake are selectively engageable to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member; a power transfer assembly having a first transfer gear and a second transfer gear, wherein the first transfer gear is rotatably fixed to the output member and the second transfer gear is rotatably fixed to a drive shaft; a power transfer member rotatably coupling the first and second transfer gears for transferring rotational energy from the first transfer gear to the second transfer gear; a final drive planetary gear set coupled to the drive shaft for receiving a driving torque from the second transfer gear; and a differential gear set coupled to the final drive planetary gear set and to a pair of road wheels for receiving a final drive rotational torque and transferring the final drive torque to the pair of road wheels.
 5. The transaxle of claim 4, wherein the power transfer member is a chain or a belt.
 6. The transaxle of claim 4 wherein the first clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the ring gear member of the fourth planetary gear set, the second clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the planet carrier member of the first planetary gear set and the input member, the third clutch is selectively engageable to interconnect the planet carrier member of the first planetary gear set and the input member with the sun gear members of the third and fourth planetary gear sets, the fourth clutch is selectively engageable to interconnect the ring gear member of the first planetary gear set and the sun gear member of the second planetary gear set with the sun gear members of the third and fourth planetary gear sets, and the brake is selectively engageable to interconnect the ring gear member of the fourth planetary gear set to the housing.
 7. The transaxle of claim 6 wherein the first clutch is disposed in the sixth area, the second clutch is disposed in the first area, the third clutch is disposed in the fifth area, the fourth clutch is disposed in the third area, and the brake is disposed in the fifth area.
 8. A transaxle comprising: an input member; an output member; a housing having a first wall, a second wall, and a third wall extending between the first and second walls; first, second, third and fourth planetary gear sets disposed within the housing, wherein the first planetary gear set is adjacent the first wall, the fourth planetary gear set is adjacent second wall, the second planetary gear set is adjacent the first planetary gear set and the third planetary gear set is between the second and fourth planetary gear sets, each planetary gear set having a sun gear member, a ring gear member, and a planet carrier member supporting a plurality of planet gears each configured to intermesh with both the sun gear member and the ring gear member, and wherein the ring gear member of the first planetary gear set is permanently coupled to the sun gear member of the second planetary gear set, the ring gear member of the second planetary gear set is permanently coupled to the planet carrier member of the third planetary gear set, the ring gear member of the third planetary gear set is permanently coupled to the planet carrier member of the fourth planetary gear set, the sun gear member of the third planetary gear set is permanently coupled to the sun gear member of the fourth planetary gear set, the output member is permanently coupled with the carrier member of the fourth planetary gear set, the input member is permanently coupled with the carrier member of the first planetary gear set, and the sun gear member of the first planetary gear set is permanently coupled to third wall of the housing, and wherein the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the first planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and second planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the second and third planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall; a first clutch disposed in at least one of the second, third, fourth, fifth, and sixth areas; a second clutch disposed in at least one of the first, second, and sixth areas; a third clutch disposed in at least one of the third, fourth, fifth and sixth areas; a fourth clutch disposed in at least one of the second, third, and fifth areas; a brake disposed in at least one of the second, third, fourth, fifth, and sixth areas, and wherein the clutches and the brake are selectively engageable to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member; a transfer gear train having a first transfer gear intermeshed with a second transfer gear, wherein the first transfer gear is rotatably fixed to the output member and the second transfer gear is rotatably fixed to an intermediate shaft; a differential gear set for driving a pair of road wheels; a pinion gear rotatably fixed to the intermediate shaft; and an input differential gear in mesh with the pinion gear and configured to rotatably drive the differential gear set.
 9. The transaxle of claim 8 wherein the first clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the ring gear member of the fourth planetary gear set, the second clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the planet carrier member of the first planetary gear set and the input member, the third clutch is selectively engageable to interconnect the planet carrier member of the first planetary gear set and the input member with the sun gear members of the third and fourth planetary gear sets, the fourth clutch is selectively engageable to interconnect the ring gear member of the first planetary gear set and the sun gear member of the second planetary gear set with the sun gear members of the third and fourth planetary gear sets, and the brake is selectively engageable to interconnect the ring gear member of the fourth planetary gear set to the housing.
 10. The transaxle of claim 9 wherein the first clutch is disposed in the second area, the second clutch is disposed in the second area, the third clutch is disposed in the fifth area, the fourth clutch is disposed in the third area, and the brake is disposed in the fifth area.
 11. A transaxle comprising: an input member; an output member; a housing having a first wall, a second wall, and a third wall extending between the first and second walls; first, second, third and fourth planetary gear sets disposed within the housing, wherein the first planetary gear set is adjacent the first wall, the fourth planetary gear set is adjacent second wall, the second planetary gear set is adjacent the first planetary gear set and the third planetary gear set is between the second and fourth planetary gear sets, each planetary gear set having a sun gear member, a ring gear member, and a planet carrier member supporting a plurality of planet gears each configured to intermesh with both the sun gear member and the ring gear member, and wherein the ring gear member of the first planetary gear set is permanently coupled to the sun gear member of the second planetary gear set, the ring gear member of the second planetary gear set is permanently coupled to the planet carrier member of the third planetary gear set, the ring gear member of the third planetary gear set is permanently coupled to the planet carrier member of the fourth planetary gear set, the sun gear member of the third planetary gear set is permanently coupled to the sun gear member of the fourth planetary gear set, the output member is permanently coupled with the carrier member of the fourth planetary gear set, the input member is permanently coupled with the carrier member of the first planetary gear set, and the sun gear member of the first planetary gear set is permanently coupled to the third wall of the housing, and wherein the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the first planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and second planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the second and third planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall; a first clutch disposed in at least one of the second, third, fourth, fifth, and sixth areas; a second clutch disposed in at least one of the first, second, and sixth areas; a third clutch disposed in at least one of the third, fourth, fifth and sixth areas; a fourth clutch disposed in at least one of the second, third, and fifth areas; a brake disposed in at least one of the second, third, fourth, fifth, and sixth areas, and wherein the clutches and the brake are selectively engageable to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member; a power transfer assembly having a first transfer gear and a second transfer gear, wherein the first transfer gear is rotatably fixed to the output member and the second transfer gear is rotatably fixed to a drive shaft; a power transfer member rotatably coupling the first and second transfer gears for transferring rotational energy from the first transfer gear to the second transfer gear; a final drive planetary gear set coupled to the drive shaft for receiving a driving torque from the second transfer gear; and a differential gear set coupled to the final drive planetary gear set and to a pair of road wheels for receiving a final drive rotational torque and transferring the final drive torque to the pair of road wheels.
 12. The transaxle of claim 11, wherein the power transfer member is a chain or a belt.
 13. The transaxle of claim 11 wherein the first clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the ring gear member of the fourth planetary gear set, the second clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the planet carrier member of the first planetary gear set and the input member, the third clutch is selectively engageable to interconnect the planet carrier member of the first planetary gear set and the input member with the sun gear members of the third and fourth planetary gear sets, the fourth clutch is selectively engageable to interconnect the ring gear member of the first planetary gear set and the sun gear member of the second planetary gear set with the sun gear members of the third and fourth planetary gear sets, and the brake is selectively engageable to interconnect the ring gear member of the fourth planetary gear set to the housing.
 14. The transaxle of claim 13 wherein the first clutch is disposed in the second area, the second clutch is disposed in the second area, the third clutch is disposed in the fifth area, the fourth clutch is disposed in the third area, and the brake is disposed in the fifth area.
 15. A transaxle comprising: an input member; an output member; a housing having a first wall, a second wall, and a third wall extending between the first and second walls; first, second, third and fourth planetary gear sets disposed within the housing, wherein the second planetary gear set is adjacent the first wall, the fourth planetary gear set is adjacent second wall, the first planetary gear set is adjacent the second planetary gear set and the third planetary gear set is between the first and fourth planetary gear sets, each planetary gear set having a sun gear member, a ring gear member, and a planet carrier member supporting a plurality of planet gears each configured to intermesh with both the sun gear member and the ring gear member, and wherein the ring gear member of the first planetary gear set is permanently coupled to the sun gear member of the second planetary gear set, the ring gear member of the second planetary gear set is permanently coupled to the planet carrier member of the third planetary gear set, the ring gear member of the third planetary gear set is permanently coupled to the planet carrier member of the fourth planetary gear set, the sun gear member of the third planetary gear set is permanently coupled to the sun gear member of the fourth planetary gear set, the output member is permanently coupled with the carrier member of the fourth planetary gear set, the input member is permanently coupled with the carrier member of the first planetary gear set, and the sun gear member of the first planetary gear set is permanently coupled to the housing, and wherein the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the second planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and second planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and third planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall; a first clutch disposed in at least one of the first, second, third, fourth, fifth, and sixth areas; a second clutch disposed in at least one of the first, second, and sixth areas; a third clutch disposed in at least one of the third, fourth, fifth and sixth areas; a fourth clutch disposed in at least one of the second, third, and sixth areas; a brake disposed in at least one of the first, second, third, fourth, fifth, and sixth areas, and wherein the clutches and the brake are selectively engageable to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member; a transfer gear train having a first transfer gear intermeshed with a second transfer gear, wherein the first transfer gear is rotatably fixed to the output member and the second transfer gear is rotatably fixed to an intermediate shaft; a differential gear set for driving a pair of road wheels; a pinion gear rotatably fixed to the intermediate shaft; and an input differential gear in mesh with the pinion gear and configured to rotatably drive the differential gear set.
 16. The transaxle of claim 15 wherein the first clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the ring gear member of the fourth planetary gear set, the second clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the planet carrier member of the first planetary gear set and the input member, the third clutch is selectively engageable to interconnect the planet carrier member of the first planetary gear set and the input member with the sun gear members of the third and fourth planetary gear sets, the fourth clutch is selectively engageable to interconnect the ring gear member of the first planetary gear set and the sun gear member of the second planetary gear set with the sun gear members of the third and fourth planetary gear sets, and the brake is selectively engageable to interconnect the ring gear member of the fourth planetary gear set to the housing.
 17. The transaxle of claim 16 wherein the first clutch is disposed in the sixth area, the second clutch is disposed in the first area, the third clutch is disposed in the third area, the fourth clutch is disposed in the third area, and the brake is disposed in the sixth area.
 18. A transaxle comprising: an input member; an output member; a housing having a first wall, a second wall, and a third wall extending between the first and second walls; first, second, third and fourth planetary gear sets disposed within the housing, wherein the second planetary gear set is adjacent the first wall, the fourth planetary gear set is adjacent second wall, the first planetary gear set is adjacent the second planetary gear set and the third planetary gear set is between the first and fourth planetary gear sets, each planetary gear set having a sun gear member, a ring gear member, and a planet carrier member supporting a plurality of planet gears each configured to intermesh with both the sun gear member and the ring gear member, and wherein the ring gear member of the first planetary gear set is permanently coupled to the sun gear member of the second planetary gear set, the ring gear member of the second planetary gear set is permanently coupled to the planet carrier member of the third planetary gear set, the ring gear member of the third planetary gear set is permanently coupled to the planet carrier member of the fourth planetary gear set, the sun gear member of the third planetary gear set is permanently coupled to the sun gear member of the fourth planetary gear set, the output member is permanently coupled with the carrier member of the fourth planetary gear set, the input member is permanently coupled with the carrier member of the first planetary gear set, and the sun gear member of the first planetary gear set is permanently coupled to the housing, and wherein the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the second planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and second planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and third planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall; a first clutch disposed in at least one of the first, second, third, fourth, fifth, and sixth areas; a second clutch disposed in at least one of the first, second, and sixth areas; a third clutch disposed in at least one of the third, fourth, fifth and sixth areas; a fourth clutch disposed in at least one of the second, third, and sixth areas; a brake disposed in at least one of the first, second, third, fourth, fifth, and sixth areas, and wherein the clutches and the brake are selectively engageable to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member; a power transfer assembly having a first transfer gear and a second transfer gear, wherein the first transfer gear is rotatably fixed to the output member and the second transfer gear is rotatably fixed to a drive shaft; a power transfer member rotatably coupling the first and second transfer gears for transferring rotational energy from the first transfer gear to the second transfer gear; a final drive planetary gear set coupled to the drive shaft for receiving a driving torque from the second transfer gear; and a differential gear set coupled to the final drive planetary gear set and to a pair of road wheels for receiving a final drive rotational torque and transferring the final drive torque to the pair of road wheels.
 19. The transaxle of claim 18, wherein the power transfer member is a chain or a belt.
 20. The transaxle of claim 18 wherein the first clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the ring gear member of the fourth planetary gear set, the second clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the planet carrier member of the first planetary gear set and the input member, the third clutch is selectively engageable to interconnect the planet carrier member of the first planetary gear set and the input member with the sun gear members of the third and fourth planetary gear sets, the fourth clutch is selectively engageable to interconnect the ring gear member of the first planetary gear set and the sun gear member of the second planetary gear set with the sun gear members of the third and fourth planetary gear sets, and the brake is selectively engageable to interconnect the ring gear member of the fourth planetary gear set to the housing.
 21. The transaxle of claim 20 wherein the first clutch is disposed in the sixth area, the second clutch is disposed in the first area, the third clutch is disposed in the third area, the fourth clutch is disposed in the third area, and the brake is disposed in the sixth area.
 22. A transaxle comprising: an input member; an output member; a housing having a first wall, a second wall, and a third wall extending between the first and second walls; first, second, third and fourth planetary gear sets disposed within the housing, wherein the second planetary gear set is adjacent the first wall, the fourth planetary gear set is adjacent second wall, the first planetary gear set is adjacent the second planetary gear set and the third planetary gear set is between the first and fourth planetary gear sets, each planetary gear set having a sun gear member, a ring gear member, and a planet carrier member supporting a plurality of planet gears each configured to intermesh with both the sun gear member and the ring gear member, and wherein the ring gear member of the first planetary gear set is permanently coupled to the sun gear member of the second planetary gear set, the ring gear member of the second planetary gear set is permanently coupled to the planet carrier member of the third planetary gear set, the ring gear member of the third planetary gear set is permanently coupled to the planet carrier member of the fourth planetary gear set, the sun gear member of the third planetary gear set is permanently coupled to the sun gear member of the fourth planetary gear set, the output member is permanently coupled with the carrier member of the fourth planetary gear set, the input member is permanently coupled with the carrier member of the first planetary gear set, and the sun gear member of the first planetary gear set is permanently coupled to the housing, and wherein the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the second planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and second planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and third planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall; a first clutch disposed in at least one of the first, second, third, fourth, fifth, and sixth areas; a second clutch disposed in at least one of the first, second, third, fourth, fifth, and sixth areas; a third clutch disposed in at least one of the third, fourth, and sixth areas; a fourth clutch disposed in at least one of the second, third, and sixth areas; a brake disposed in at least one of the first, second, third, fourth, fifth, and sixth areas, and wherein the clutches and the brake are selectively engageable to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member; a transfer gear train having a first transfer gear intermeshed with a second transfer gear, wherein the first transfer gear is rotatably fixed to the output member and the second transfer gear is rotatably fixed to an intermediate shaft; a differential gear set for driving a pair of road wheels; a pinion gear rotatably fixed to the intermediate shaft; and an input differential gear in mesh with the pinion gear and configured to rotatably drive the differential gear set.
 23. The transaxle of claim 22 wherein the first clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the ring gear member of the fourth planetary gear set, the second clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the planet carrier member of the first planetary gear set and the input member, the third clutch is selectively engageable to interconnect the planet carrier member of the first planetary gear set and the input member with the sun gear members of the third and fourth planetary gear sets, the fourth clutch is selectively engageable to interconnect the ring gear member of the first planetary gear set and the sun gear member of the second planetary gear set with the sun gear members of the third and fourth planetary gear sets, and the brake is selectively engageable to interconnect the ring gear member of the fourth planetary gear set to the housing.
 24. The transaxle of claim 23 wherein the first clutch is disposed in the sixth area, the second clutch is disposed in the first area, the third clutch is disposed in the third area, the fourth clutch is disposed in the third area, and the brake is disposed in the fifth area.
 25. A transaxle comprising: an input member; an output member; a housing having a first wall, a second wall, and a third wall extending between the first and second walls; first, second, third and fourth planetary gear sets disposed within the housing, wherein the second planetary gear set is adjacent the first wall, the fourth planetary gear set is adjacent second wall, the first planetary gear set is adjacent the second planetary gear set and the third planetary gear set is between the first and fourth planetary gear sets, each planetary gear set having a sun gear member, a ring gear member, and a planet carrier member supporting a plurality of planet gears each configured to intermesh with both the sun gear member and the ring gear member, and wherein the ring gear member of the first planetary gear set is permanently coupled to the sun gear member of the second planetary gear set, the ring gear member of the second planetary gear set is permanently coupled to the planet carrier member of the third planetary gear set, the ring gear member of the third planetary gear set is permanently coupled to the planet carrier member of the fourth planetary gear set, the sun gear member of the third planetary gear set is permanently coupled to the sun gear member of the fourth planetary gear set, the output member is permanently coupled with the carrier member of the fourth planetary gear set, the input member is permanently coupled with the carrier member of the first planetary gear set, and the sun gear member of the first planetary gear set is permanently coupled to the housing, and wherein the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the second planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and second planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first and third planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall; a first clutch disposed in at least one of the first, second, third, fourth, fifth, and sixth areas; a second clutch disposed in at least one of the first, second, third, fourth, fifth, and sixth areas; a third clutch disposed in at least one of the third, fourth, and sixth areas; a fourth clutch disposed in at least one of the second, third, and sixth areas; a brake disposed in at least one of the first, second, third, fourth, fifth, and sixth areas, and wherein the clutches and the brake are selectively engageable to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member; a power transfer assembly having a first transfer gear and a second transfer gear, wherein the first transfer gear is rotatably fixed to the output member and the second transfer gear is rotatably fixed to a drive shaft; a power transfer member rotatably coupling the first and second transfer gears for transferring rotational energy from the first transfer gear to the second transfer gear; a final drive planetary gear set coupled to the drive shaft for receiving a driving torque from the second transfer gear; and a differential gear set coupled to the final drive planetary gear set and to a pair of road wheels for receiving a final drive rotational torque and transferring the final drive torque to the pair of road wheels.
 26. The transaxle of claim 25, wherein the power transfer member is a chain or a belt.
 27. The transaxle of claim 26 wherein the first clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the ring gear member of the fourth planetary gear set, the second clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the planet carrier member of the first planetary gear set and the input member, the third clutch is selectively engageable to interconnect the planet carrier member of the first planetary gear set and the input member with the sun gear members of the third and fourth planetary gear sets, the fourth clutch is selectively engageable to interconnect the ring gear member of the first planetary gear set and the sun gear member of the second planetary gear set with the sun gear members of the third and fourth planetary gear sets, and the brake is selectively engageable to interconnect the ring gear member of the fourth planetary gear set to the housing.
 28. The transaxle of claim 20 wherein the first clutch is disposed in the sixth area, the second clutch is disposed in the first area, the third clutch is disposed in the third area, the fourth clutch is disposed in the third area, and the brake is disposed in the fifth area.
 29. A transaxle comprising: an input member; an output member; a housing having a first wall, a second wall, and a third wall extending between the first and second walls; first, second, third and fourth planetary gear sets disposed within the housing, wherein the third planetary gear set is adjacent the first wall, the first planetary gear set is adjacent second wall, the fourth planetary gear set is adjacent the third planetary gear set and the second planetary gear set is between the fourth and first planetary gear sets, each planetary gear set having a sun gear member, a ring gear member, and a planet carrier member supporting a plurality of planet gears each configured to intermesh with both the sun gear member and the ring gear member, and wherein the ring gear member of the first planetary gear set is permanently coupled to the sun gear member of the second planetary gear set, the ring gear member of the second planetary gear set is permanently coupled to the planet carrier member of the third planetary gear set, the ring gear member of the third planetary gear set is permanently coupled to the planet carrier member of the fourth planetary gear set, the sun gear member of the third planetary gear set is permanently coupled to the sun gear member of the fourth planetary gear set, the output member is permanently coupled with the carrier member of the fourth planetary gear set, the input member is permanently coupled with the carrier member of the first planetary gear set, and the sun gear member of the first planetary gear set is permanently coupled to the housing, and wherein the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the third planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth and second planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the second and first planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall; a first clutch disposed in at least one of the first, second, third, and sixth areas; a second clutch disposed in at least one of the third, fourth, and fifth areas; a third clutch disposed in at least one of the first, second, fifth, and sixth areas; a fourth clutch disposed in at least one of the first, second, fifth, and sixth areas; a brake disposed in at least one of the first, second, third, and sixth areas, and wherein the clutches and the brake are selectively engageable to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member; a transfer gear train having a first transfer gear intermeshed with a second transfer gear, wherein the first transfer gear is rotatably fixed to the output member and the second transfer gear is rotatably fixed to an intermediate shaft; a differential gear set for driving a pair of road wheels; a pinion gear rotatably fixed to the intermediate shaft; and an input differential gear in mesh with the pinion gear and configured to rotatably drive the differential gear set.
 30. The transaxle of claim 29 wherein the first clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the ring gear member of the fourth planetary gear set, the second clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the planet carrier member of the first planetary gear set and the input member, the third clutch is selectively engageable to interconnect the planet carrier member of the first planetary gear set and the input member with the sun gear members of the third and fourth planetary gear sets, the fourth clutch is selectively engageable to interconnect the ring gear member of the first planetary gear set and the sun gear member of the second planetary gear set with the sun gear members of the third and fourth planetary gear sets, and the brake is selectively engageable to interconnect the ring gear member of the fourth planetary gear set to the housing.
 31. The transaxle of claim 30 wherein the first clutch is disposed in the sixth area, the second clutch is disposed in the fourth area, the third clutch is disposed in the fifth area, the fourth clutch is disposed in the fifth area, and the brake is disposed in the sixth area.
 32. A transaxle comprising: an input member; an output member; a housing having a first wall, a second wall, and a third wall extending between the first and second walls; first, second, third and fourth planetary gear sets disposed within the housing, wherein the third planetary gear set is adjacent the first wall, the first planetary gear set is adjacent second wall, the fourth planetary gear set is adjacent the third planetary gear set and the second planetary gear set is between the first and fourth planetary gear sets, each planetary gear set having a sun gear member, a ring gear member, and a planet carrier member supporting a plurality of planet gears each configured to intermesh with both the sun gear member and the ring gear member, and wherein the ring gear member of the first planetary gear set is permanently coupled to the sun gear member of the second planetary gear set, the ring gear member of the second planetary gear set is permanently coupled to the planet carrier member of the third planetary gear set, the ring gear member of the third planetary gear set is permanently coupled to the planet carrier member of the fourth planetary gear set, the sun gear member of the third planetary gear set is permanently coupled to the sun gear member of the fourth planetary gear set, the output member is permanently coupled with the carrier member of the fourth planetary gear set, the input member is permanently coupled with the carrier member of the first planetary gear set, and the sun gear member of the first planetary gear set is permanently coupled to the housing, and wherein the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the third planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth and second planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the second and first planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall; a first clutch disposed in at least one of the first, second, third, and sixth areas; a second clutch disposed in at least one of the third, fourth, and fifth areas; a third clutch disposed in at least one of the first, second, fifth, and sixth areas; a fourth clutch disposed in at least one of the first, second, fifth, and sixth areas; a brake disposed in at least one of the first, second, third, and sixth areas, and wherein the clutches and the brake are selectively engageable to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member; a power transfer assembly having a first transfer gear and a second transfer gear, wherein the first transfer gear is rotatably fixed to the output member and the second transfer gear is rotatably fixed to a drive shaft; a power transfer member rotatably coupling the first and second transfer gears for transferring rotational energy from the first transfer gear to the second transfer gear; a final drive planetary gear set coupled to the drive shaft for receiving a driving torque from the second transfer gear; and a differential gear set coupled to the final drive planetary gear set and to a pair of road wheels for receiving a final drive rotational torque and transferring the final drive torque to the pair of road wheels.
 33. The transaxle of claim 32, wherein the power transfer member is a chain or a belt.
 34. The transaxle of claim 32 wherein the first clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the ring gear member of the fourth planetary gear set, the second clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the planet carrier member of the first planetary gear set and the input member, the third clutch is selectively engageable to interconnect the planet carrier member of the first planetary gear set and the input member with the sun gear members of the third and fourth planetary gear sets, the fourth clutch is selectively engageable to interconnect the ring gear member of the first planetary gear set and the sun gear member of the second planetary gear set with the sun gear members of the third and fourth planetary gear sets, and the brake is selectively engageable to interconnect the ring gear member of the fourth planetary gear set to the housing.
 35. The transaxle of claim 34 wherein the first clutch is disposed in the sixth area, the second clutch is disposed in the fourth area, the third clutch is disposed in the fifth area, the fourth clutch is disposed in the fifth area, and the brake is disposed in the sixth area.
 36. A transaxle comprising: an input member; an output member; a housing having a first wall, a second wall, and a third wall extending between the first and second walls; first, second, third and fourth planetary gear sets disposed within the housing, wherein the second planetary gear set is adjacent the first wall, the first planetary gear set is adjacent second wall, the third planetary gear set is adjacent the second planetary gear set and the fourth planetary gear set is between the first and third planetary gear sets, each planetary gear set having a sun gear member, a ring gear member, and a planet carrier member supporting a plurality of planet gears each configured to intermesh with both the sun gear member and the ring gear member, and wherein the ring gear member of the first planetary gear set is permanently coupled to the sun gear member of the second planetary gear set, the ring gear member of the second planetary gear set is permanently coupled to the planet carrier member of the third planetary gear set, the ring gear member of the third planetary gear set is permanently coupled to the planet carrier member of the fourth planetary gear set, the sun gear member of the third planetary gear set is permanently coupled to the sun gear member of the fourth planetary gear set, the output member is permanently coupled with the carrier member of the fourth planetary gear set, the input member is permanently coupled with the carrier member of the first planetary gear set, and the sun gear member of the first planetary gear set is permanently coupled to the housing, and wherein the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the second planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the second and third planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth and first planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall; a first clutch disposed in at least one of the first, second, third, and sixth areas; a second clutch disposed in at least one of the first, third, fourth, and sixth areas; a third clutch disposed in at least one of the fourth, fifth, and sixth areas; a fourth clutch disposed in at least one of the second, third, fourth, fifth, and sixth areas; a brake disposed in at least one of the first, second, third, fourth, and sixth areas, and wherein the clutches and the brake are selectively engageable to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member; a transfer gear train having a first transfer gear intermeshed with a second transfer gear, wherein the first transfer gear is rotatably fixed to the output member and the second transfer gear is rotatably fixed to an intermediate shaft; a differential gear set for driving a pair of road wheels; a pinion gear rotatably fixed to the intermediate shaft; and an input differential gear in mesh with the pinion gear and configured to rotatably drive the differential gear set.
 37. The transaxle of claim 36 wherein the first clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the ring gear member of the fourth planetary gear set, the second clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the planet carrier member of the first planetary gear set and the input member, the third clutch is selectively engageable to interconnect the planet carrier member of the first planetary gear set and the input member with the sun gear members of the third and fourth planetary gear sets, the fourth clutch is selectively engageable to interconnect the ring gear member of the first planetary gear set and the sun gear member of the second planetary gear set with the sun gear members of the third and fourth planetary gear sets, and the brake is selectively engageable to interconnect the ring gear member of the fourth planetary gear set to the housing.
 38. The transaxle of claim 37 wherein the first clutch is disposed in the first area, the second clutch is disposed in the first area, the third clutch is disposed in the fifth area, the fourth clutch is disposed in the fifth area, and the brake is disposed in the sixth area.
 39. A transaxle comprising: an input member; an output member; a housing having a first wall, a second wall, and a third wall extending between the first and second walls; first, second, third and fourth planetary gear sets disposed within the housing, wherein the second planetary gear set is adjacent the first wall, the first planetary gear set is adjacent second wall, the third planetary gear set is adjacent the second planetary gear set and the fourth planetary gear set is between the first and third planetary gear sets, each planetary gear set having a sun gear member, a ring gear member, and a planet carrier member supporting a plurality of planet gears each configured to intermesh with both the sun gear member and the ring gear member, and wherein the ring gear member of the first planetary gear set is permanently coupled to the sun gear member of the second planetary gear set, the ring gear member of the second planetary gear set is permanently coupled to the planet carrier member of the third planetary gear set, the ring gear member of the third planetary gear set is permanently coupled to the planet carrier member of the fourth planetary gear set, the sun gear member of the third planetary gear set is permanently coupled to the sun gear member of the fourth planetary gear set, the output member is permanently coupled with the carrier member of the fourth planetary gear set, the input member is permanently coupled with the carrier member of the first planetary gear set, and the sun gear member of the first planetary gear set is permanently coupled to the housing, and wherein the housing has a first area defined radially inward from an outer periphery of the planetary gear sets and axially bounded by the first wall and the second planetary gear set, a second area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the second and third planetary gear sets, a third area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the third and fourth planetary gear sets, a fourth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the fourth and first planetary gear sets, a fifth area defined radially inward from the outer periphery of the planetary gear sets and axially bounded by the first planetary gear set and the second wall, and a sixth area defined radially inward from the third wall and radially outward from the outer periphery of the planetary gear sets and axially bounded by the first wall and the second wall; a first clutch disposed in at least one of the first, second, third, and sixth areas; a second clutch disposed in at least one of the first, third, fourth, and sixth areas; a third clutch disposed in at least one of the fourth, fifth, and sixth areas; a fourth clutch disposed in at least one of the second, third, fourth, fifth, and sixth areas; a brake disposed in at least one of the first, second, third, fourth, and sixth areas, and wherein the clutches and the brake are selectively engageable to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member; a power transfer assembly having a first transfer gear and a second transfer gear, wherein the first transfer gear is rotatably fixed to the output member and the second transfer gear is rotatably fixed to a drive shaft; a power transfer member rotatably coupling the first and second transfer gears for transferring rotational energy from the first transfer gear to the second transfer gear; a final drive planetary gear set coupled to the drive shaft for receiving a driving torque from the second transfer gear; and a differential gear set coupled to the final drive planetary gear set and to a pair of road wheels for receiving a final drive rotational torque and transferring the final drive torque to the pair of road wheels.
 40. The transaxle of claim 39, wherein the power transfer member is a chain or a belt.
 41. The transaxle of claim 39 wherein the first clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the ring gear member of the fourth planetary gear set, the second clutch is selectively engageable to interconnect the planet carrier member of the second planetary gear set with the planet carrier member of the first planetary gear set and the input member, the third clutch is selectively engageable to interconnect the planet carrier member of the first planetary gear set and the input member with the sun gear members of the third and fourth planetary gear sets, the fourth clutch is selectively engageable to interconnect the ring gear member of the first planetary gear set and the sun gear member of the second planetary gear set with the sun gear members of the third and fourth planetary gear sets, and the brake is selectively engageable to interconnect the ring gear member of the fourth planetary gear set to the housing.
 42. The transaxle of claim 41 wherein the first clutch is disposed in the first area, the second clutch is disposed in the first area, the third clutch is disposed in the fifth area, the fourth clutch is disposed in the fifth area, and the brake is disposed in the sixth area. 